Every bride and groom dream of a great party at their wedding reception, and in most cases, that dream includes a packed dancefloor. Keep the dancefloor full by planning your reception start time with sunset in mind - this is especially important in the summer months when the sun doesn't go down until around 8:30pm.
Think about it: your favorite club doesn't have fluorescent lightbulbs or natural light streaming in because people prefer to dance in darker, ambient atmospheres. Too much light makes people self conscious and shy, and your dancefloor will be anemic as a result. Also, any candlelight you've used in your decor won't have any impact if your reception space is flooded with natural light. If your venue has any kind of windows, use this sunset calculator to determine when the sun will go down and schedule your reception accordingly.